Studies on the coronary collateral circulation will continue with investigation of protection of the heart provided by these channels. In addition, the role of noninvasive radionuclide angiocardiography will continue at an augmented rate. This technique is quite simple and provides objective measurements of cardiac output, pulmonary blood flow to each lung, left ventricular end-diastolic volume, left ventricular systolic volume, pulmonary transit time, and left ventricular ejection fraction. Using this approach, a variety of studies will be done in patients with ischemic heart disease both in relation to selection for specific revascularization procedures and to the status of cardiac competence in this group in relation to the need for general surgical procedures.